eventTargetData(): pull (most of) this singleton off-heap.

third_party/WebKit/Source/core/dom/Node.cpp

Index: third_party/WebKit/Source/core/dom/Node.cpp
diff --git a/third_party/WebKit/Source/core/dom/Node.cpp b/third_party/WebKit/Source/core/dom/Node.cpp
index 54d7625aef662cc8155465ebfbcaacf9ae8a9e59..caf5618827c3424f3f6e8939958d3761287ee1f4 100644
--- a/third_party/WebKit/Source/core/dom/Node.cpp
+++ b/third_party/WebKit/Source/core/dom/Node.cpp
@@ -1882,9 +1882,9 @@ void Node::removeAllEventListenersRecursively() {
 }
 
 using EventTargetDataMap =
-    HeapHashMap<WeakMember<Node>, Member<EventTargetData>>;
+    PersistentHeapHashMap<WeakMember<Node>, Member<EventTargetData>>;
 static EventTargetDataMap& eventTargetDataMap() {
-  DEFINE_STATIC_LOCAL(EventTargetDataMap, map, (new EventTargetDataMap));
+  DEFINE_STATIC_LOCAL(EventTargetDataMap, map, ());
   return map;
 }